The present invention relates to weighing machines for weighing off batches of material, said weighing machines comprising a steel construction on which a central distributor, a plurality of transporters and a plurality of scales are mounted, and wherein the transporters are arranged around the central distributor and configured with a view to transporting material from the distributor and radially outwards from the central distributor and to the scales.
Today such weighing machines are used essentially for forming batches of bulk material of a weight that is very close to a desired reference weight such that the batches can be transferred to e.g. a packaging machine that packages the individual batches.
Such weighing machines that are often designated combination weights operate in that each of the scales are, by means of the transporters, filled with a batch portion of the bulk material that was initially supplied to the central distributor and then, via the central distributor, transferred to the individual transporters. The individual batch portion is subsequently weighed off the bulk product into the individual scales, and by means of a calculator or computer the scales are found that combine to contain a bulk product that is close to the desired reference weight. Finally the calculator is configured to effect that the thus identified scales are emptied to form the total batch of the bulk product, and since it is possible to continuously form and identify combinations of scales that combine to contain the desired amount, such machines enable very elevated production rates while generating a large number of material batches exhibiting very small variations in their weight.
However, it is a problem in connection with the prior art machines to be used for this purpose that it is necessary to configure the central distributor as well as the individual transporters such that there is a certain amount of clearance there between, and since there is often a considerable amount of the bulk material present in these parts of the machine, practice has shown that it is difficult to avoid that material, be it individual loose objects or fluid, passes through the clearances present between the central distributor and the transporters, and between the transporters as such.
Thus, in case of the prior art machinery it is often necessary to perform regular cleaning of the machine, such material constituents being susceptible to deposit on the frame parts of the machine with for instance an ensuing sanitary hazard.
In the light of this it is the object of the present invention to provide a weighing machine of the kind described above whereby such sanitary hazards have been completely or partially overcome.
According to the invention this is obtained in that the weighing machine comprises one or more substantially uninterrupted shields in the form of screen faces that extend from somewhere underneath the distributor and outwards and downwards below at least that end of the transporter that faces towards the central distributor, seen in the operative position of the machine.
According to a preferred embodiment of the invention the transporters of the weighing machine is configured such that they comprise a groove with a first end that faces towards the central distributor and a second, open end that faces towards one or more scales; and wherein the groove is delimited by two lateral edges that extend between the first and the second open ends.
The screen faces in the weighing machine can preferably comprise frustoconical or upwardly convex, rounded faces that can be configured from a plate material in a simple manner.
To this end, the screen faces may advantageously comprise cylindrical faces that extend from a frustoconical face and downwards from the lower edge thereof whereby, the screen face can be configured such that its distance from the central distributor, the transporters and for instance scales can be adapted in such a manner that material that drops onto the screen face does not drop too rapidly.
Particularly advantageously a collector groove is configured at the lower edge of the screen faces with a view to collecting material that drops from the distributor or the transporters, and that willxe2x80x94via the screen facesxe2x80x94be conveyed down into the collector groove. Hereby cleaning of the machine, if to be performed, is enabled with liquids without the liquids continuing down into a subjacent packing machine, if any, and that for instance liquids from the bulk material portioned in the machine and that run down through the clearances, e.g. between the individual transporters and the central distributor, do not drip into the packaging machine or the packagings.
In this context the collector grooves advantageously features an outlet in particular for liquids that are collected in the collector groove.
According to a further preferred embodiment of the invention the screen faces constitute a part of the weighing machine""s frame construction, and the central distributor, the transporters and/or the scales are mounted on the screen face by means of fittings intended therefor. Hereby it is possiblexe2x80x94with the screen facesxe2x80x94to construct an extremely vibration-free shell construction that will support the individual constituents that are mounted thereon in a stable manner.
To this end the fittings can advantageously be configured such that they permit material that runs or slides down the screen face to run or slide past the fitting, an in accordance with a particularly simple embodiment of the fittings, they comprise substantially planar plate flanges that are secured to the screen face in such a manner that the plane of the plate flange extends substantially vertically or slantingly downwards.
Advantageously, the weighing machine comprises a computer ia for collecting weighing data from the scales and for controlling the transporters; and wherein at least a part of the weighing machine computer is arranged below the screen face thereby avoiding a considerable amount of wirings from an external computer and which also means that the computer is still well shielded against soiling and humidity.
Further advantageously a number of liquid nozzles can be configured above the screen face, said nozzles being connected to a conduit for liquids with a view to sweeping and cleaning the screen face with cleaning liquid. This enables extremely simple cleaning of the machine when necessary.
According to an embodiment that is particularly suitable for portioning material that consists of solid components the screen face can extend substantially uninterrupted from a point underneath the central distributor and out underneath the other end of the grooves. This is due to the fact that primarily the solid components, have a tendency to travel out between the spaces that are located between the individual transporters and the screen face will thereby effectively catch such solid components.